<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>String</title>
    <script>
        var first = "外'双内'单";
        console.log(first);
        var second = '外"单内"双';
        console.log(second);
        console.log("WDNMD\nWDNMD");
    </script>
</head>
<body>
</body>
</html>